This invention relates to picture image reading systems and particularly to reading systems which divide a light beam transmitted through or reflected from a picture image medium such as an exposed X-ray film or an image plate into a plurality of light beams and read wide density regions where the wide density region is separated into a plurality of read-out density regions corresponding to the plurality of light beams for separate processing of the properties thereof.
In conventional picture image reading systems, a light beam passed through or reflected from a picture image film such as an X-ray film is divided into a plurality of light beams for the measurement of the properties of each, where each is converted into an electric signal. Each reader operates with, for instance, the quantity of light distributed among a plurality of readers or the quality of photoelectric conversion sensitivity being set different from each other where the readers read different density regions, respectively. Then the electric signals of the density readers each are connected and synthesized according to the sensitivity ratio of each density reader to effect density reading in a wide region.
However, the disadvantages of such a reading system include, because of difficulty in setting the sensitivity of each density reader and fluctuation in the read-out density data due to fluctuation in the sensitivity of the read-out density data in terms time or temperature, the read-out density data of adjoining read-out density regional portions of the density readers become discontinuous or overlap when the read-out density data are connected and synthesized, thus filing to connect and synthesize the read-out density data from the readers with accuracy.